Microsoft Excel - Permission Denied Error for CreateObject("Excel.application")

I'm getting a VBScript Error (70: Permission Denied) when my VBScript runs via the Windows Scheduler and I try to create an instance of Excel.application [Set mobjExcel = CreateObject("Excel.Application")]. This is only happening on some of our production servers. It works fine on or DEV/QA servers. All servers have Same OS (Windows 2003 R3) .The same code runs successfully on the production in the following instances:

1> If I run it manually.

2> If I do a logon to the Server as the same user and the scheduled script runs in my shell.

Code Snippet:

Here is a test script. code fails on Set mobjExcel = CreateObject("Excel.Application")

If (Err.Number <> 0) Then

mfhLogFile.WriteLine ("Error creating instance of Excel Object. Error Details: " & Chr(10) & _

Err.Number & ": " & Err.Description)

Else

mfhLogFile.WriteLine ("No Error Writing to Audit File")

End If

mfhLogFile.Close

mobjExcel.Application.Quit

Set mobjExcel = nothing

Set gobjFSO = nothing

End sub

---------------------------------------------------

Any help/input ?

Thanks

sincerely
Shashin